Around half of emissions of nitrogen oxides (NOx) - these contribute to illegal levels of nitrogen dioxide (NO2) - and particulate matter (PM) come from transport.
These pollutants make chronic illnesses worse, shorten life expectancy and can damage lung development.
The communities suffering most from poor air quality are often the most vulnerable, including the children of London. At least 360 primary schools are in areas exceeding safe legal pollution levels.
Reports we've relied on for this information are listed on the Ultra Low Emission Zone page in Publications & reports.
To help improve the air we breathe we're introducing measures to encourage more walking, cycling, use of public transport and to encourage more efficient freight deliveries. We've also been working to create a bus fleet that emits less pollution as well as cleaner taxis and cleaner private hire vehicles.
ULEZ is another way to help reduce the most harmful emissions generated by road transport in central London and across the Capital.
The introduction of the ULEZ will help reduce exhaust NOx and PM emissions, helping to improve air quality and making central London a safer and more pleasant place to live, work and visit.
These positive effects will be especially beneficial to the young, older people and those who have respiratory problems, as well as residents of high pollution areas.
The majority of traffic entering the ULEZ will be from outside the zone, so the benefits of cleaner, greener vehicles in the form of reduced emissions will be experienced across London, even to areas not in the zone.